FIELD OF THE INVENTION
This invention relates to well servicing equipment, and more particularly to apparatus for conducting pressurized fluids from a service vehicle to a wellhead.
During the course of producing fluids from a petroleum well it often becomes desirable or necessary to subject the well to a treatment procedure in order to stimulate its fluid production. That procedure usually involves the injection of a fluid under high pressure, such as 20,000 psi., to fracture the producing earth formation, or the injection of an acid solution to dissolve or otherwise remove flow obstructing material, thereby increasing the flow of petroleum from the formation into the well. In order to carry out these well stimulation procedures, it is commonplace to employ an articulate pipe assembly, called a service line, to conduct the fluid from a mobile pumping unit to the wellhead. Such a service line usually comprises a plurality of straight lengths of rigid pipe interconnected end-to-end by pipe swivel joints, and sufficient pipe unions to facilitate disassembly into sections that can be handled manually.
Although this type of service line is functionally satisfactory, there are disadvantages associated with its installation and removal. For example, the procedure generally employed is to transport the disassembled line by truck or other vehicle to the well site and then manually unload the pipe sections, position them between the wellhead and the pumping unit, and interconnect them into a fluid-tight conduit. Each of these steps takes significant time and requires trained personnel, both of which are costly. When pipe of larger than normal diameter, and thus of greater weight, is used in order to increase the volume of fluid injected into the well in a given time period, or to reduce the time for injecting a given fluid volume, additional personnel and/or time are required. In either case the procedure is not as efficient as desired.
Various ways to overcome these disadvantages have been proposed, including the use of telescoping and other types of cranes with single or double booms to assist in handling the pipe sections. However, considerable side load tending to overturn the crane is encountered, due either to a small load at extreme horizontal distance or a large load at extreme vertical distance, thereby requiring the crane to possess an extremely heavy center of gravity, or necessitating the use of outriggers to widen the base and keep within decent engineering practices of loading. Both solutions are awkward in that they frequently exceed highway load limits on single wheel-single axle euipment, and sometimes even the bearing load of the earth over which the crane must travel to the well site. A further disadvantage of outriggers is that they inhibit the location and placement of pumper or feeder trucks at the well site. Resorting to separate tractors skip loaders, side boom loaders, and other such devices does not fully overcome these problems if, as is sometimes the case, impassable areas between these vehicles and the well site are encountered.